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Eye-centered encoding of visual space in scene-selective regions.
Emily J Ward1, Sean P MacEvoy, Russell A Epstein
1Department of Psychology and Center for Cognitive Neuroscience, University of Pennsylvania, PA, USA. emily.ward@yale.edu
Journal of Vision
|December 8, 2010
Summary
Researchers investigated visual scene processing using fMRI. Contrary to predictions, the parahippocampal place area (PPA) and transverse occipital sulcus (TOS) use eye-centered encoding, not head or world frames.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Visual Perception
Background:
- Cortical visual hierarchy neurons have retina-based receptive fields (RFs).
- Scene-processing regions like PPA, RSC, and TOS were hypothesized to use head, body, or world-centered RFs.
Purpose of the Study:
- To investigate the reference frames used for visual information encoding in scene-responsive cortical areas.
- To determine if PPA, RSC, and TOS utilize eye-centered, head-centered, body-centered, or world-centered reference frames.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was employed to study brain activity.
- Subjects viewed objects and scenes at various screen locations while maintaining fixation at different gaze positions.
- Response profiles were analyzed based on fixation-referenced and screen-referenced positions.
Main Results:
- The parahippocampal place area (PPA) and transverse occipital sulcus (TOS) demonstrated eye-centered encoding, with RFs shifting based on fixation point.
- The retrosplenial complex (RSC) did not show a clear position-response curve in either tested reference frame.
- Findings indicate a shared eye-centered encoding mechanism between PPA/TOS and other visual processing regions.
Conclusions:
- PPA and TOS employ eye-centered reference frames, similar to earlier visual areas.
- The RSC's reference frame remains undetermined by this study.
- These results highlight the crucial role of PPA and TOS in visual scene analysis and suggest common encoding strategies across visual areas.
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